Belt grinding apparatus



J1me 1965 e. DENHERDER BELT GRINDING APPARATUS Filed May 31, 1963 Gerald Den Herder INVENTOR.

3,187,471 BELT GING APPARATUS Gerald Den Herder, Tacoma, Wash, assignor to Square Wheel (30., Seattle, Wash, a corporation of Washington Filed May 31, 1963, Ser. No. 284,566

6 flaims. (Cl. 51-141) This invention relates to belt grinding apparatus characterized by the following objects and'advantages.

(1) It provides in a single small, compact, relatively inexpensive apparatus, provision for grinding fiat surfaces or curved surfaces having a wide range of radii.

(2) The adjustment required to accommodate the apparatus to the grinding of various types of surfaces may be made readily and quickly.

(3) Use of the apparatus makes possible grinding accurately to very close tolerances.

(4) The working area of the apparatus is easily accessible from all working angles. I

(5) The apparatus may be applied to the grinding of relatively inaccessible work areas, as the welds on the hub of a boat propeller, between the propeller blades.

7 (6) The abrasive belt incorporated in the apparatus may be maintained under any desired degree of tension at all times.

(7) The apparatus is safe and easy'to use;

The manner is which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claims considered together with the drawings, wherein:

FIG. 1 is a view in side elevation of the herein described belt grinding apparatus;

FIG. 2 is a view in front elevation of the apparatus of FIG. 1; a

FIG. 3 is a partial view in side elevation, corresponding to FIG. 1, illustrating the application of a unique grinding head in one working position;

FIG. 4 is a partial view in side elevation, corresponding to FIG. 3, but illustrating the grinding head of that figure in a second working position; and

FIG. 5 is a detail, transverse sectional view taken along line 5-5 of FIG. 4.

Generally stated, the belt grinder of my invention comprises a frame including a base, belt drive means mounted on one end of the base, an upwardly extending bracket mounted on the other end of the base and a grinding head including an idler pulley assembly mounted on the bracket. A tensioning pulley provided with means for adjusting the belt tension also is mounted on the frame. All three pulleys, the drive pulley, the idler pulley, and the tensioning pulley are aligned and positioned for mounting an abrasive belt.

The grinding head assembly is provided with interchangeable heads, including a unique head adjustable between four positions as required to accommodate the apparatus to radius grinding, flat grinding and yoke grinding. In this manner one simple, compact apparatus is provided, which meets all of the grinding needs of the average shop.

Considering the foregoing in greater detail and with reference to the drawings: v

The grinding apparatus of the invention is mounted on a horizontal base 10 which is adapted to clamp over the edge of the work table. A frame structure including vertical side plates l2, l4is attached to the base. A grinding shield is supported on the side plates.

At one end of the base is mounted an electric motor 16 controlled by switch 13, convenientto the hand of the operator. A drive pulley 20 is fixed to the shaft of the motor. A brake 22, operated by lever 24, works on the surface of the pulley to arrest its motion quickly when desired.

- United States Patent 0 j 3,187,471 Patented June 8, 1965 Drive pulley 2t) mounts one end of a convention abrasive belt 26. The other end of this belt is supported by a grinding head assembly, one form of which is illustrated in FIGS. 1 and 2. i

.As shown in these figures, a bracket 28 extends upwardly and outwardly from base it), beyond the plane of sidewalls 12, 14, to present an exposed and readily accessible grinding area. The outer end of bracket 28 is provided with a clamp 39 which may be engaged and released by means of bolt 32.

Mounted in clamp 30 is an idler pulley assembly indicated generally at 34 and including a stationary shaft 36, side plates 38 and a rotatable rim 40.

Idler pulley 34 provides a first grinding head. It is aligned with drive pulley 20 and, together with a tensioning pulley 42, supports and mounts theabrasive belt. The tensioning pulley is so mounted and arranged as to make possible both applying any desired degree of tension to abrasive belt 26, and accommodating the assembly to the mounting of abrasive belts of different sizes.

Accordingly, the instant assembly comprises afirst or radius arm 44 having at its outer end a yoke formed by an angled plate 46 releasably bolted to the side face of radius arm 44 by means of bolt 48.

lournaled in the yoke assembly thus provided is shaft 50 of tensioning pulley 42. A ball shaped retainer 52 is formed integrally with the shaft and accurately positions the pulley.

Cooperating with radius arm 44 is an adjusting arm 54. This arm is provided with a handle 55 and'lies at an adjustable angle with respect to the radius arm. The inner ends of both arms are mounted on side plate 12 by means of a common pivot pin 55.

The outer end of adjusting arm 54 carries a spring mounting 58 while the outer end of arm 44 carries a cooperating spring mounting 69. A compression spring 62 is placed between the two mountings.

Although arm 44 moves angularly, as required to apply tensioning pulley 42 to the belt, adjusting arm 54 is maintained in an adjusted stationary position. The means employed for this purpose comprise a ratchet 64, one end of which is pivoted to the underside of adjusting arm 54 by means of pin 67. The other end of ratchet 64 moves freely, and is provided with a positioning handle 66. The teeth of ratchet 64 engage a stationary pin 68 extending I outwardly from bracket 28.

To work the tensioning device, the position of arm 54 is adjusted by means of handle 55 until spring 62 is sulficiently compressed. Ratchet 64 then is engaged with pin 68 by means of handle 66. In this manner there is provided an adjustment which may be use easily in the first instance to accommodate a newly put on belt, and which may be used later as a running adjustment toaccommodate a stretchedbelt during operation of the apparatus.

As indicated above, the grinding head provided by idler pulley assembly 34 is removable and may be replaced with other grinding heads adapted to particular work. Such an alternate head is indicated generally at '70 in FIGS. 3, 4 and 5. r

This head includes an arm preferably formed of a length of angle iron and thus provided with a side plate 72 and, at right angles, a platen 74. Side plate 72 mounts intermediate its ends a post 76 dimensioned for reception in clamp 35 At oneend of arm is a shaft 73 which mounts an idler pulley 8% at the other, a shaft 82-which mounts an idler pulley 84. Pulleys 80, 84 preferably are of different diameters, thereby providing grinding heads adaptable to work of different radii.

' Operation The operation of the herein described grinding apparatus is as follows:

Assuming that a curved surface is to be ground, a grinding head 34 including an idler pulley of appropriate diameter is selected and mounted in clamp 30. T ensioning roll 42 is adjusted by manipulation of ratchet 64. The idler assembly then provides an accessible arcuate working surface for accomplishing the grinding operation, the work area being shielded by adjustable shield 15.

If the grinding of a flat surface is contemplated, or if curved surfaces of varying radii are to be ground, then the grinding head assembly 70 of FIGS. 3-5 may be employed. This head is readily interchangeable with head 34 by loosening bolt 32, removing the one head and replacing it with the other.

Grinding head 70 is usuable in four positions. Thus it may be used in the position of FIG. 3 wherein the ground radius is determined by the size of idler pulley 34.

On the other hand, it may be used in a position rotated 180 from the position of FIG. 3, which brings pulley 80 into working position. The diameter of this pulley then determines the grinding radius.

Still further, the grinding head may be employed in the. position of FIG. 4. This brings platen 74 into its working position underlying abrasive belt 26. Accordingly fiat work may be accommodated.

If now the grinding head is rotated 180 from it's position' of FIG. 4, the area' of the grinding belt between wheels 80, 84, will be unsupported. Accordingly, a yoke contact' of the belt with the work is provided and any desired radius may be put on the Work as determined in part by the pressure applied to the belt which deforms under the pressure. In all of these situations, the grinding area of tlie'apparatus is projected beyond the frame to a readily accessible position.

In this manner there is provided a relatively simple, inexpensive apparatus which nevertheless is highly eflicient in its operation and which is versatile in providing grinding surfaces adaptable to all of the commonly encountered grinding applications found in the average shop.

It is to be understood that the'forms of my invention.

herein shown and described is to be taken as a preferred example of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. In belt grinding apparatus including an endless abrasive belt, mounting means therefor and drive means therefor, a grinding head assembly comprising:

(a) an arm,

(b) adjustable attaching means between the ends of the arm for attaching the arm to the apparatus in a predetermined position of angular adjustment,

() a pair of pulleys journaled one on each end of the arm and positioned to mount the belt, each pulley providing an arcuate backing for use in grinding arcuate surfaces having curvatures corresponding to the curvatures of the pulleys,

(d) and a platen on the arm located between the pulleys and underlying the belt.

2. The grinding head assembly of claim 1 wherein the arm and platen comprise an angle iron, one plate of the angle iron mounting the attaching means and the other plate underlying the belt and providing the platen for grinding fiat surfaces.

3. In belt grinding apparatus including an endless abrasive belt, mounting means therefor, and drive means therefor, a grinding head assembly comprising:

(a) an arm,

(h) post and clamp means for attaching the arm to the apparatus at a point intermediate the ends of the arm in a predetermined position of angular adjustment,

(c) a pair of pulleys journaled one on each end of the arm and positioned to mount the belt, and

(d) a platen on one side of the arm underlying the .belt between the pulleys,

(e) the arm being adjustable between first and second grinding positions wherein a selected one of the pulleys is in operative position for radius grinding, a third grinding position wherein the platen is in operative position for flat grinding, and a fourth position wherein an unsupported segment of the belt is in operative position for yoke grinding.

4. In belt grinding apparatus including an endless abrasive belt, mounting means therefor and drive means therefor, a belt tensioning assembly comprising:

(a) an idler pulley mounting the belt,

(b) a first arm,

(c) on the outer end of the first arm mounting means rotatably mounting the pulley,

(d) a second arm arranged at an angle to the first arm,

(e) on the outer end of the second arm resilient means engaging the first arm,

(f) pivot means mounting the inner ends of both arms,

and

(g) adjusting means attached to one of the arms for adjusting the resilient means as required to tension the .belt, the adjusting means comprising rack and retainer pin means interconnecting the second arm and the frame of the apparatus.

5. In belt grinding apparatus including an endless abrasive belt, mounting means therefor, and drive means therefor, a belt tensioning assembly comprising:

(a) an idler pulley mounting the belt,

(b) a first arm,

(0) yoke means on the outer end of the first arm,

(d) a shaft journaled in the yoke means and connected to the idler pulley,

(e) ball retainer means on the shaft between the arms of the yoke,

(f) a second arm arranged at an angle to the first,

(g) pivot pin means mounting the inner ends of both arms for angular adjustment of one with respect to the other,

(h) resilient means operatively positioned between the outer ends of the arms, and

(i) rack and pin means interconnecting the frame of the apparatus and the second arm for varying the angular adjustment between the arms, thereby adjusting the tension applied to the .belt by the idler pulley.

6. Belt grinding apparatus comprising:

(a) a base,

(b) a frame extending upwardly from the base,

(0) a drive pulley mounted at one end of the base,

((1) a bracket extending upwardly from the other end of the base,

(e) post and clamp means on the upward end of the bracket,

(f) an angle iron, one plate of the angle iron being secured intermediate its ends to the post,

(g) the clamp means securing the post releasably for adjusting the angle iron in a predetermined angular position,

(h) the other plate of the angle iron providing a platen for grinding flat surfaces,

(i) a pair of pulleys journaled one on each end of the said one plate of the angle iron in alignment with tab? drive pulley for mounting an endless abrasive (j) the pair of pulleys being of different diameters and each providing an arcuate backing for use in grinding arcuate surfaces having curvatures corresponding to the curvatures of thepulleys,

(k) the angle iron being adjustable between first and second grinding positions wherein a selected one of the pulleys is in operative position for radius grinding, a third grinding position wherein the platen is in operative position underlying the belt for fiat 3,1 Y 5 grinding, and a fourth position wherein an unsupported segment of the belt is in operative position for yoke grinding, (l) a first arm, V (m) yoke means on the outer end of the first arm, (n) a shaft journaled in the yoke means, (0) ball retainer means on the shaft between the arms of the yoke, (p) an idler pulley mounted on the shaft in alignment with the first named pulleys, (q) a second arm arranged at an angle to the first arm, (r) pivot pin means on the frame mounting the inner ends of both arms for angular adjustment of one with respect to the other,

(s) resilient means operatively positioned between the outer ends of the arms, and

(t) rack and pin means interconnecting the frame and the second arm for varying the angular adjustment between the arms, thereby adjusting the tension applied to the belt by the idler pulley.

References Cited by the Examiner UNITED STATES PATENTS 10 1,434,334 10/22 Freeman 51-41 1,554,925 9/25 Showers 51-41 2,259,941 10/41 Primeaux. 2,3 13,25 4

3/43 Mead 51148 LESTER M. SWINGLE, Primary Examiner. 

1. IN BELT GRINDING APPARATUS INCLUDING AN ENDLESS ABRASIVE BELT, MOUNTING MEANS THEREFOR AND DRIVE MEANS THEREFOR, A GRINDING HEAD ASSEMBLY COMPRISING: (A) AN ARM, (B) ADJUSTABLE ATTACHING MEANS BETWEEN THE ENDS OF THE ARM FOR ATTACHING THE ARM TO THE APPARATUS IN A PREDETERMINED POSITION OF ANGULAR ADJUSTMENT, (C) A PAIR OF PULLEYS JOURNALED ONE ON EACH END OF THE ARM AND POSITIONED TO MOUNT THE BELT, EACH PULLEY PROVIDING AN ARCUATE BACKING FOR USE IN GRINDING ARCUATE SURFACES HAVING CURVATURES CORRESPONDING TO THE CURVATURES OF THE PULLEYS, (D) AND A PLATEN ON THE ARM LOCATED BETWEEN THE PULLEYS AND UNDERLYING THE BELT. 